In the conventional hydraulically operated braking system used in trucks, automobiles and other wheeled vehicles, depression of the brake pedal applies braking pressure simultaneously to front and rear wheels and release of the pedal releases this pressure simultaneously from all of such wheels.
In my invention operable open-close valve remotely operated from the dashboard of a vehicle is disposed in the hydraulic supply line in such manner as to either prevent hydraulic fluid from being applied to the front wheels (when the valve is closed) or to permit the fluid to be applied to the front wheels in conventional manner (when the valve is opened).
In use, when the valve is closed prior to application of brake pressure, the front wheels will spin freely and braking action is only effective at the rear wheels. Drivers will find this arrangement extremely useful when driving on slick or icy roads, since better control is obtained.
When the valve is closed subsequent to application of brake pressure, the front wheels are locked even after brake pressure is released. This action provides a braking assist when the vehicle is parked on a steep hill or the like.